In order to accurately calculate the discharge energy of high frequency inverter resistance welding power supply， the energy loss in the power supply circuit was quantified. On the basis of precise modeling， the effectiveness of PSpice physical device simulation model is verified by circuit simulation. Based on the parametric quantified energy consumption model， the main loss of power circuit is analyzed by fitting integral method， which provides reference for the design of power prototype. The simulation results show that the finite bipolar soft switching technology can effectively reduce the switching loss of the high-frequency inverter circuit， and the synchronous rectifier circuit loss accounts for 69% of the total power loss. Therefore， the structure and thermal loop of the high-frequency transformer and synchronous rectifier integrated design of the power supply should be considered.